fix number of overflow bugs affecting threaded version

make current_op faster.


git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1615 b08c6af1-5177-4d33-ba66-4b1c6b8b522a

changes-5.1.html

@@ -16,6 +16,9 @@
 
 <h2>Yap-5.1.2:</h2>
 <ul>
+<li> FIXED: make current_op only walk over atoms.</li>
+<li> FIXED: memory corruption when copying consult stack (obs Paulo Moura).</li>
+<li> FIXED: get rid of some silly locks.</li>
 <li> FIXED: don't compare block top with <= (obs Paulo Moura).</li>
 <li> FIXED: ! was not pruning right in p_execute_clause (obs Nicos
   Angelopoulos).</li>